Wells are sometimes drilled into a formation so that fluids can be injected into that formation to stimulate production into another well that is drilled into that same formation. These wells are called injection wells. Typically, the injection well is cased and a liner is suspended with a hanger from the cemented casing above. The liner is perforated and one or more zones in the zone in question are isolated with barriers such as packers. The injection fluid is applied between barriers into the formation in question for injection into the formation to stimulate production through another well in that same formation.
The problem that occurs is that the injected fluid between the barriers and into a formation is generally significantly colder than ambient formation temperature. As a result of long periods of injection, the temperature of the liner pipe that supports the isolation packers or other barriers used to direct the injection flow begins to change to the injection temperature. This usually means that the liner between packers cools and as a result shrinks. Just how much is a function of the coefficient of thermal expansion or contraction for the given material of the liner and the temperature difference. It is not unforeseen to have contraction in the order of 0.3 inches per 20 foot of liner length for a temperature difference of greater than 100 degrees Centigrade. Temperature changes of at least 50 degrees Centigrade are all too common. When fairly large packer spacing is employed, the amount of liner shrink can be significant enough to pull one or both packers loose or damage one or more of the packers to the point where they don't hold a seal. Testing has shown that the amount of force required to impose a counteracting tensile force to cancel out the shrinkage effect could be an axial force in the order of over 50,000 thousand pounds.
Telescoping cylinders have been used downhole for centralizing a tubular in a wellbore to leave an annular space around the tubular for a good cement job. These telescoping cylinders can be pushed out when the tubular is in position. Some illustrations of this type of centralizing system can be found in U.S. Pat. Nos. 5,228,518; 5,346,016; 5,379,838; 5,224,556; and 5,165,478. In yet another application, these cylinders have been designed with removable barriers to let flow go through them after extension. Extendable elements with flow passages and screens are illustrated in US Publication Number 2006/0108114 A1. In that respect they eliminated a perforating step for casing. Telescoping pistons have also been designed with sensors and are illustrated in U.S. Pat. No. 5,829,520.
The present invention addresses the damage and loss of seal risk to isolation packers in injection service by resisting the induced thermal forces to hold the liner supporting the packers against dimension change that can damage them or make them lose seal through axial movement. These and other advantages of the present invention will become more apparent to those skilled in the art from a review of the description of the preferred embodiment and the drawings that appear below while recognizing that the claims fully define the scope of the invention.